4.4-stable review patch. If anyone has any objections, please let me know.
------------------
From: Eugene Syromiatnikov esyr@redhat.com
commit 6dd0d2d22aa363fec075cb2577ba273ac8462e94 upstream.
For some reason, the implementation of some 16-bit ID system calls (namely, setuid16/setgid16 and setfsuid16/setfsgid16) used type cast instead of low2highgid/low2highuid macros for converting [GU]IDs, which led to incorrect handling of value of -1 (which ought to be considered invalid).
Discovered by strace test suite.
Cc: stable@vger.kernel.org Signed-off-by: Eugene Syromiatnikov esyr@redhat.com Signed-off-by: Heiko Carstens heiko.carstens@de.ibm.com Signed-off-by: Martin Schwidefsky schwidefsky@de.ibm.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- arch/s390/kernel/compat_linux.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-)
--- a/arch/s390/kernel/compat_linux.c +++ b/arch/s390/kernel/compat_linux.c @@ -110,7 +110,7 @@ COMPAT_SYSCALL_DEFINE2(s390_setregid16,
COMPAT_SYSCALL_DEFINE1(s390_setgid16, u16, gid) { - return sys_setgid((gid_t)gid); + return sys_setgid(low2highgid(gid)); }
COMPAT_SYSCALL_DEFINE2(s390_setreuid16, u16, ruid, u16, euid) @@ -120,7 +120,7 @@ COMPAT_SYSCALL_DEFINE2(s390_setreuid16,
COMPAT_SYSCALL_DEFINE1(s390_setuid16, u16, uid) { - return sys_setuid((uid_t)uid); + return sys_setuid(low2highuid(uid)); }
COMPAT_SYSCALL_DEFINE3(s390_setresuid16, u16, ruid, u16, euid, u16, suid) @@ -173,12 +173,12 @@ COMPAT_SYSCALL_DEFINE3(s390_getresgid16,
COMPAT_SYSCALL_DEFINE1(s390_setfsuid16, u16, uid) { - return sys_setfsuid((uid_t)uid); + return sys_setfsuid(low2highuid(uid)); }
COMPAT_SYSCALL_DEFINE1(s390_setfsgid16, u16, gid) { - return sys_setfsgid((gid_t)gid); + return sys_setfsgid(low2highgid(gid)); }
static int groups16_to_user(u16 __user *grouplist, struct group_info *group_info)